[lug] need cat5 wiring/"Dest host unreachable" help
jkarns at csd.net
Fri Oct 19 20:40:09 MDT 2001
I've encountered problems similar to what you describe when installing
cat-5 cable due to excessive cable length.
If the length of your patch cords (cables having the RJ-45 connectors on
them) exceeds 5 meters, that could be your problem. Patch cords are
spec'd to have a maximum length of 5 meters. I assume this is due to high
signal attenuation characteristics of the RJ-45 connectors. For cables
exceeding 5 meters, you need to use a jack, which installs with a punch
tool. That type of connector minimizes the attenuation. Along those
lines, I would also check that the wire connections to the jacks are "well
pinched". Even though a continuity check will reveal a good connection,
characteristics are quite different at 100 Mhz. Finally, I would try
connecting the two floating pair.
On Thu, 18 Oct 2001, Michael J. Hammel said:
> I'm trying to wire my upstairs game room to my downstairs office with
> CAT5 cable. The cable was already run when the house was built. But
> the connections were mucked up. So I'm trying to fix them.
> My office has a gateway connected to a hub with 3 other computers
> (including a laptop) hooked directly into the hub. All that works
> fine. I connected the CAT5 cable in the wall to an CAT5 jack and
> moved the cable that was running to the laptop from the hub into the
> wall. Upstairs I used the same wiring combination on the jack (see
> below) and plugged another cable from that jack into my laptop.
> I get a link light on the laptops connector (external pcmcia type) and
> on the hub. However, when I ping anyone on the downstairs net from
> the laptop upstairs (or reverse the direction) I get "Destination Host
> Unreachable". I think the wiring is correct. But I can't ping anyone
> on opposite floors.
> I doubt the cable is over 100 meters in total length, so that
> shouldn't be the problem. None of the cabled used to plug the laptop
> into the wall or the wall into the hub is a crossover cable, so that's
> the not the problem.
> Is the timeout for the ping expiring and making it look like the
> remote hosts can't be reached? Should any of the transmit/receive
> wires be crossed?
> I used the T568B standards for the wiring and run in straight through.
> The wire from downstairs runs to a junction box where it is connected
> straight through to to the wire that runs to the wall in the game
> Anyone got any suggestions? Some of the twists came out of the wires
> so I added them back in (I've heard that helps reduce noise). But
> that didn't help. The green/green-white pairs seem to provide link
> lights. The orange/orange-white pairs seem to provide data. Is that
> correct? The blue/blue-white and brown/brown-white pairs are unused
> as far as I know. Those latter sets are currently unconnected.
John Karns jkarns at csd.net
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